••• NL932 NO CLEAN LEAD FREE SOLDER PASTE

NL932 No Clean Lead Free Solder Paste

The NL932, manufactured by FCT Solder, delivers Surface Area Ratio (SAR) paste transfer efficiencies below 0.6 and 0.55 respectively. NL932 is formulated to deliver
exceptional cosmetics, especially when used in conjunction with Nihon Superior’s SN100C patented lead free alloy. It was specially designed to meet the requirements for reliable solder joints in printed circuit board assemblies.

Printing
Stencil aperture design and stencil quality are major factors in achieving excellent print consistency with any lead free solder paste. Laser Cut stencils from Stencils Unlimited are recommended for optimal print performance, and can be custom designed to minimize and improve the yields of any process. Some general stencil aperture design guidelines follow:

Discrete components
A 0.002” reduction (L & W) for water washable and a 0.002” reduction (L & W), with “U-shaped” home-plates, for no clean to minimize mid-chip solder beads.

Printer Operation

Solder Paste Bead Size:

2cm (~0.75”) on startup

Add when bead < 1.4 cm (~0.5”)

Squeegee:

Metal, Slic™ blade preferred

60 degrees from horizontal

Speed

25 to 150 mm/sec. (1 to 6 in/sec)

Adjust printer for a pull or print demand process

Pressure:

0.18-0.27 Kg/cm (squeegee length)

Underside Wipe:

Slic™ and Ultraslic™ stencils should exceed >10 prints/wipe

Stencil life / Environment:

>8 hours

30-65% RH and 20º C – 25º C

Tack Life:

24hrs @ 25°C / 45% RH

Tack Force:

1.5 grams/mm2

Slump 0.7mm Pads:

0.4 @ 25°C / 1Hour

0.4 @ 80°C / 20 minutes

Slump 1.5mm Pads:

0.4 @ 25°C / 1Hour

0.4 @ 80°C / 20 minutes

Storage and Handling

Cartridges should be stored tip down.

No Clean Paste can be stored up to two weeks at room temperature.

To prolong the shelf life of NL932, refrigerate between 5°C~10°C, (41°F~50°F). At this range the shelf life will exceed 8 months.

NL932 should not be allowed to freeze.

When refrigerated, lead free solder paste must be allowed to warm up to room temperature.

Lead Free Paste must be >= 22°C, (~66°F) prior to applying to stencil for processing.

Working range of NL932 is between 22-32°C, (~66°F - 89.5°F).

First-In-First-Out (FIFO) inventory management practices should be used with all lead free solder pastes.

Heating
A linear ramp of 0.7°C to 2.0°C C/second is suggested to gradually remove the solvents and other volatile components in the lead free solder paste. This also helps in minimizing solder balls, beading and bridging from hot slump.
A linear ramp also helps minimize depletion of flux activity which can occur with excessive temperature, preheat times, and at very high reflow temperatures.
A profile with a soak between 200-210°C for less than 20 seconds can be used to reduce void formation on BGA and CSP devices. (Request FCTA’s profile guide to void reduction).
While a linear profile typically does not produce tombstoning, a short 10-20 second dwell prior to transitioning into the liquidus point of the solder, and minimizing the QR between soak and liquid temperatures will help minimize tombstoning if experienced.

Cooling
A cooling rate of 3°C-4°C per second is recommended for most lead/free reflow applications. These parameters should be utilized to insure a fine grain solder structure and minimal IMC layer.